Method of controlling predatory fish



Aug. 9, 1966 R. E. HART 3,254,772

METHOD OF CONTROLLING PREDATORY FISH Original Filed Nov 6, 1963 3Sheets-Sheet l l NVENTOR. flay/M0 f fix r Aug. 9, 1966 R. E. HART3,264,772

METHOD OF CONTRQLLING PREDATORY FISH Original Filed Ncv 6, 1963 2SheetsSheet 8 [nmlnunun 4 mnmn...

73v" 7 72 i' INVENTOR.

7J/LVT/2? 74 J 6/54 424 Ahzr United States atent 3,264,772 METHQD FCONTRGLLKNG PREDATORY FISH Richard E. Hart, Torrance, alif., assignor toDouglas Aircraft Company, Inc, Santa Monica, Calif. Original applicationNov. 6, 1963, Ser. No. 321,840, now Patent No. 3,199,454, dated Aug. 10,1965. Divided and this application Dec. 16, 1964, Ser. No. 418,823

6 Claims. (Cl. 434.5)

This is a division of application Serial No. 321,840, filed November 6,1963, now Patent No. 3,199,454.

My invention relates generally to means for controlling predatory marinelife such as sharks in various situations including protection of nettedfish and the net during fishing operations, warding off of sharks andthe like from attacking a person or persons floating in the ocean duringrescue operations thereof, and other operations of a gen,- erallyanalogous nature. In particular, my invention relates to a novel anduseful device for producing a repellent and deterrent barrier topredatory fish at any desired position and time within a fluid mediumsuch as the ocean.

Predatory fishes, especially sharks, present quite a problem in oceanfishing Where a net is utilized to catch fish such as tuna. The tunaclippers carry extremely large nets which are used to capture a schoolof tuna when sighted or found. Purse seines are normally used and arequite large, being of the order of 400 fathoms in length and 45 fathomsin depth. When a school of tuna is found, a power skiff is put outpulling one end of the large net or sein from the aft platform of thetuna clipper bringing the net before and across the path of the tunaschool. The clipper than circles and brings its end of the net togetherwith the end on the skiff. The upper edge of the net is, of course,supported by floats and the lower edge is weighted by steel ringsthrough which the purse line passes. When the ends of the net arebrought together, the ends of the purse line are wound up by a powerwinch on the clipper to draw together the bottom or lower edge of thenet and thus trap the tuna therein.

After the bottom of the purse net is closed and brought on board of theclipper, one end of the net is tied down and the other end is brought upand passed over a boommounted block or drum which is rotatably driven totake up the net that is then stacked on the aft platform. The purseline, of course, is detached from the winch as required. The net size isthus progressively reduced and formed into a relatively small bag orsack from which the tuna is scooped and deposited in the fish wells ofthe clipper by a process commonly referred to as brailing.

It is in the process of taking up the net, especially during pickup ofthe last 100 fathoms of the net, that the largest percentage of sharkattacks occur. Very few attacks occur after the tuna are brought to thebag. Also, there is no Warning as to when the attacks will occur; thefirst indication comes when large net holes caused by the sharks appearas the net is picked up via the power block or drum. Thus, at times, notonly is a large part of the tuna catch lost, the destruction to the netmay necessitate patching thereof for periods of hours to days.

The net holes caused by the sharks, and therefore their attacks on thetuna, occur approximately 80 percent of the time in the rolling strip ofthe net. The net is formed of a large number of horizontal orlongitudinal strips which are normally 3 /2 fathorns wide or deep. Asthe net is being picked up, the tuna which became gilled or caught inthe net meshes at or near the rolling strip and those that are rolledtherein by the upward movement of the net, appear to induce the sharksto attack mostly at that time.

The rolling strip is seven strips down from the upper edge of the net,so that the shark attacks usually occur at a depth of approximately 21to 24 /2 fathoms. Actual- "ice ly, the depth is somewhat less due to thecurvature of the net as it is being taken up. Even so, this order ofdepth renders it very difficult to provide any effective measures, if atall, which would prevent the shark attacks. A similar problem of depthis present in finding effective measures to prevent shark attacks on aperson or persons floating on the surface of the water during rescueoperations since sharks normally approach anywhere from the surface ofthe ocean to depths of about 10 feet and initiate their attack effort onthe victims from a depth of 3 to 5 feet.

It is an object of my invention to provide means which can be usedeffectively to repel and deter predatory fish such as sharks fromattacking netted fish at a considerable depth in the ocean, or a personor persons floating on the surface thereof.

Another object of the invention is to provide means capable of producinga barrier at any selected depth, and which barrier is an effectiverepellent and deterrent to predatory fish such as sharks.

A further object of the invention is to provide a relatively small andlight device which can be controlled in sink rate in a fluid medium andis capable of producing a comparatively large barrier at a desireddepth.

A still further object of this invention is to provide a relativelysimple, highly effective and substantially selfcontained means forproducing a large volume, cloud formation barrier at a desired depth inthe ocean whereby predatory fishes are actively repelled from it by thecharacteristic nature of the barrier.

Briefly, and in general terms, the foregoing and other objects arepreferably accomplished by providing a pyrotechnic cartridge containingtherein a quantity of repellent material and an explosive charge havingone end of a predetermined length of fuse connected thereto, thecartridge including a ballast of a predetermined shape and weight at oneend to govern the sink rate of the cartridge in a fluid medium, and aprimer or initiator assembly (fusee unit) connecting with the other endof the fuse at another end of the cartridge. By igniting the primer anddeploying the cartridge to a point as desired on the ocean, thecartridge will sink at a predetermined rate for a time durationestablished by the length of fuse therein before detonation thereof at aproper depth occurs. The explosion then disperses the repellentsubstance in a large cloud formation to provide a barrier to predatoryfish by virtue of the chemical and physical characteristics of thebarrier.

The repellent material in the cartridge is a chemical compositioncomprising a mixture of variable proportions preferably of a Watersoluble fluorescent substance, fine sand and a toxic or highlydisagreeable ingredient to predatory fish. The latter ingredient ispreferably copper sulfate which, however, can be entirely omitted fromthe chemical composition since it was discovered that the fine sand, incertain uses of the cartridge, is sufi'iciently irritating in thebarrier to predatory fish such as sharks to permit the omission of thetoxic ingredient from the chemical composition. Instead of coppersulfate, creosote may be used forming a colloidal solution or mixturewith the other ingredients.

My invention will be more fully understood, and other objects andfeatures thereof will become apparent from the following detaileddescription of an illustrative embodiment of the invention, to be takenin connection with the attached drawings, in which:

FIGURE 1 is a side view of an illustrative embodiment of my invention;

FIGURE 2 is a central, longitudinal sectional view of the predatory fishcontrol cartridge taken along the line 22 as indicated in FIGURE 1;

FIGURE 3 is a fragmentary, sectional view of an end 3 of the cartridgetaken along the line 33 as indicated in FIGURE 2;

FIGURE 4 is a simplified perspective view taken generally from above thewater depicting the use of the cartridge in fishing operations; and

FIGURE 5 is a perspective view taken from another direction andincluding a portion underwater to illustrate the use of the cartridge infishing operations.

FIGURE 1 is a side view of an illustrative embodiment of my invention. Asubstantially symmetrical cartridge which is generally cylindrical inshape is shown. The cartridge 10 has an overall length of, for example,approximately 5 /8 inches, and has a diameter of approximately 2 /2inches. A tubular casing 12 forms the main body of the cartridge 10. Thecasing 12 is preferably a cylindrical, cardboard tubing (or equivalent)which is approximately 4 inches in length, has a wall thickness of about.05 inch and an outside diameter of approximately 2% inches which is, ofcourse, the main diameter of the cartridge 10.

A ballast 14 which is cylindrically shaped and having a hemisphericalend 16, is attached to one end 18 of the tubular casing 12 such that thecasing 12 is closed by the ballast 14 at that end and the hemisphericalend 16 forms a streamlined front end for the cartridge 10. The ballast14 is preferably fabricated from a cement substance which may be similarto the trade name sealers Pour Rock or Hydrocal. A mixture of fine sandand the cement substance may be used if the total weight of the ballast14 is to exceed, for example, .4 lb.

It is desirable that the cement substance used to fabricate the ballast14 have a specific gravity of at least 2.80 in order that the size ofthe ballast 14 be kept reasonably small. While the ballast 14 could, ofcourse, be greatly reduced in size if a metallic substance were used, itwould be more diflicult and expensive to produce a streamlinedhemispherical end of suitable diameter to close the end 18 of thetubular casing 12.

A ballast 14 fabricated from a suitable cement substance can also bemore easily shattered when mounted in close proximity to an explosivecharge and is generally safer than a metallic ballast under suchcircumstances. A metallic ballast 14 having a hemispherical end,however, can be made centrally .hollow and this may be desirable forcertain applications where it is necessary to provide greater spacewithin the cartridge 10 without increasing its overall size.

A casing 12a having a closed left end such as a hemispherical end 16aindicated in phantom lines, may be used instead of the tubular casing12. The casing 12a is preferably made of plastic material extruded inthe shape indicated, and the ballast 14 is produced by pouring asuitable amount of cement substance into the hemispherical end 16a ofthe casing 12a and allowed to harden therein.

FIGURE 2 is a central, longitudinal sectional view of the cartridge 10taken along the line 22 as indicated in FIGURE 1. The cylindricallyshaped ballast 14 has a beveled peripheral edge at the inner end whichis swage fitted into the end 18 of the casing 12. The beveled edge 20makes, for example, an angle of degrees with the longitudinal axis ofthe cylindrically shaped ballast 14, and is approximately inch widelongitudinally. The ballast 14 is approximately 2 inches long, having a1 inch spherical radius for its hemispherical end 16. It should be notedthat the ballast 14 can be varied in material, shape and size asrequired. In fact, a ballast 14 fabricated from a cement substance hasmore bulk than one made of a metallic substance, for a hemispherical endof a predetermined radius, which would permit easier reduction in sizeand/or machining to alter the weight and shape of the ballast to controlthe sink rate of the cartridge 10 in a fluid medium as desired forvarious purposes.

The inner end of the ballast 14 is swage fitted approximately inchlongitudinally into the left end 18 of the casing 12 as indicated inFIGURE 2. The ballast 14 is somewhat loosely secured to the end of thecasing by immersing the cartridge 10, when fully completed, in ordinarymolten parafiin. The other, right end 22 of the tubular casing 12 isclosed by a cap or plug 24 which is preferably A1 inch thick, hardmarine plywood disc having a port 26 provided centrally therein.

A quantity of chemical composition 28 and an explosive charge 30 havinga connecting fuse 32 are contained within the casing 12 in the spacebetween the ballast 14 and the plug 24. The chemical composition 28 ispacked about the explosive charge 30 and its fuse 32 which arepreferably positioned and arranged approximately as shown in FIGURE 2.The chemical composition 28 comprises a mixture of different materialswhich can be varied in type and/ or relative amounts as desired orrequired for different uses of the cartridge 10. The type and/ or amountof explosive charge 30 and the type and/ or length of the fuse 32 canalso be varied as desired or required for different uses of thecartridge 10.

The cartridge 10 is designed to control predatory marine life such assharks, barracuda, etc. it can be used effectively during pickup of anet in ocean fishing operations to reduce or eliminate the loss ofnetted fish and the destruction of large portions of the net by sharks.The cartridge 10 can also be used to ward off or repel a shark attack ona person or persons floating or swimming in the ocean following thesinking of a disabled aircraft or ship, for example, while rescueoperations are underway. The chemical composition 28 is preferablydifferent in mixture proportions for use in fishing operations than inrescue operations. Similarly, the composition of the ballast 14, thequantity of explosive charge 30 and the length of its fuse 32 are alsonormally different for these operations.

For use in predatory fish control, the chemical composition 28preferably comprises a mixture of a water soluble fluorescent substanceto provide a visible fluorescence when dissolved in water, :a finelydivided inorganic solid material to serve as a carrier and dispersingagent and to provide an iopaque-formin g as wellias arespiratory-irritating substance carrying barrier, and a toxic ordisagreeable substance to predatory fish. The chemical composition 28,for example, preferably comprises a mixture of sodium fiuorescein (Na CH O fine sand or silicone dioxide (SiO and finely powdered coppersulphate (CuSO -l-5H O). These substances are all intimately andthoroughly mixed together to form the chemical composition 28. Creosote,CH O.C H .(CH OH), may be used in place of the copper sulfate, and isintimately mixed with the other ingredients to form a firm mass.

The explosive charge 30 is, for example, a perchlorate, black aluminumflash powder and the fuse 32 is preferably a black powder trail fusewhich is moisture proof. The fuse 32 is approximately /a inch indiameter, for example, and burns at a predetermined rate. The explosivecharge 30 is also contained in a moisture proof container of relativelythin plastic or suitably treated paper. Although considerableobservations were made and extensive tests were conducted aboard the MSParamount in the Central American fishery (San Benedicto) and aboard theMS Antoinette B in the Central and South American fisheries, whichestablished the effectiveness and usefulness of the cartridge 10 and itspreferred chemical composition 28, it was not determined just to whatextent the chemical characteristics of the explosive perchlorate charge30, on detonation and dispersal of the chemical composition 28, added tothe chemical repellent nature of the composition 28. It is believed thatthe exploded perchlorate charge 30 serves primarily to disperse thechemical composition 28 in a cloud formation.

It was discovered that the fine sand or silica ingredient of thechemical composition 28 appeared to have a significantly irritatingeffect on predatory fish such as sharks. In fact, where there is undueconcern that the copper sulphate, which is a limited poison, maypossibly cause contamination or damage to netted fish from injection ofthe copper sulphate into the ocean close to the fish, it is possible toomit the copper sulphate, or other toxic ingredient that might be usedinstead, from the chemical composition 28 without greatly reducing therepellent or deterrent efifect of the cloud formation in the waterresulting from explosion of the cartridge 10. Of course, there is littlefear of contamination when creosote is used in place of the coppersulfate since creosote is comrmonly used in the preservation of wood andsmoked meat.

Actually, fish contamination due to dispersal of some copper sulphate inthe ocean is essentially nil through use of a pyrotechnic cartridge ascompared to the injection of a sulphate solution by means of a hose to apoint in the ocean near the surface and the ship where the net is beingpicked up. The cartridge produces a cloud formation at a depth anddistance which will not be picked up and collected by the net as it isbeing raised, and any sulphate that might be encountered by the nettedfish or net is washed away by the time that the fish or net is broughtup and into the ship.

Three examples listing the ingredients and various proportions by volumeof satisfactory mixtures of the chemical composition 28 for use infishing operations are given below. A fairly wide, permissible variationin proportions of ingredients is indicated.

EXAMPLE A Ingredient Parts by Volume Sodium fluorescein 2 2 3 Fine and(silica) 6 5 4 Finely powdered copper sulfate 2 3 3 The sodiumfiuorescein is mainly provided in the chemical composition 28 to producea visible fluorescence when it is dissolved in water, and can be omittedfrom the chemical composition if desired. However, its fluorescence isbelieved to help deter predatory fish from entering such resultantbarriers. While the toxic or disagreeable ingredient in the chemicalcomposition 28 is preferably copper sulfate or creosote, other repellentingredients such as formic acid or potassium phenyl acetate which areboth water soluble may be used in suitable mixtures.

Where the cartridge 10 is used in fishing operations, the explosivecharge 30 can consist of 120:8 grains of the perchlorate black aluminumflash powder in the illustrative cartridge 10 described above. With aballast 14 weighing approximately .4 1b., and the cartridge properlyfilled with the chemical composition 28, a fuse 32 having a burn time of28:2 seconds is preferably employed. The illustrative cartridge 10 wouldthen have a sink rate of approximately 5 feet per second, and thecartridge 10 will therefore be exploded at a depth of about feet orabout 23 fathoms which is at rolling strip depth. It should be notedthat the end of the fuse 32 is lit by a connecting primer or initiatorassembly (fusee unit) which is described below, that has a burn time ofnot greater than, for example, 2- L /z second. Thus, approximately twoseconds are available in which to aim and throw the activated cartridge10 into the ocean, and have the cartridge 10 start sinking when the fuse32 begins to burn.

In a life saving situation, as might occur during rescue operations of aperson or persons floating or swimming in the ocean and subject toattack by sharks, the toxic or disagreeable ingredient in a mixture ofthe chemical composition 28 is considerably increased in proportion. Anexample indicating the ingredients and various proportions by volume ofsatisfactory mixtures of the chemical composition 28 for use in rescueoperations are given below. A fairly wide, permissible variation inproportions of ingredients is also indicated.

The explosive charge 39 in a cartridge 10 which is used for rescueoperations, is reduced approximately in half to, for example, 60:4grains of the perchlorate black aluminum flash powder. This will reducethe hazard or danger of the explosion to nearby persons. At the sametime, it is desirable that the sink rate of the cartridge 18 be reduced,and the fuse 32 be shortened so that detonation of the cartridge 10occurs at about a depth of about 8 to 10 feet. This is to provideadequate protection from sharks which may approach from depths of about10 feet and initiate their attack effort from a depth of 3 to 5 feet.

When the cartridge 10 is to be used in rescue operations, the ballast 14is preferably fabricated from a plastic (polyurethane) substance ofplaster of Paris, for example, to reduce the sink rate to approximately3 feet per second. If the cartridge 10 is to be deployed from ahelicopter at a height of approximately 200 feet, a fall time ofapproximately 3 /2 seconds is expended before impact with the surface ofthe water. With about 2 seconds primer or fusee burn time (for aimingand throwing) and a cartridge sink rate of 3 feet per second, or 3seconds to reach a depth of 9 feet, the total time expended fromignition of a cartridge 10 to detonation thereof will be about 8 /2seconds. This amount of time provides reasonable safety for handling anddeploying the cartridge 10. However, this amount of time should not bedecreased very much, so that an unduly heavy ballast 14 should beavoided with cartridges which are used in rescue operations.

The fuse 32 is connected on one end to the explosive charge 30, and theother end is passed through the port 26 and into an aligned hole 34 in aprimer or initiator assembly for fusee unit 36 which is attached to plug24 in a spot-faced circular recess 38 thereof, as shown in FIGURE 2. Theinitiator assembly or fusee unit 36 includes a basic disc 40 having thehole 34 centrally located therein, a primer compound 42 filling acountersunk portion 44 at the outer part of hole 34, and an adhesivecover 46 for the compound 42. The outer edge of the disc 40 is beveled,and the adhesive cover 46 covers the entire end face of the disc 40including the beveled surface so that the primer compound 42 is fullysealed. The adhesive cover 46 has a non-adhesive tab 48 which can beeasily grasped to peel the cover 46 off the outer face of the fusee unit36 to uncover the primer compound 42. The primer compound 42 is similarto that used in fusees and is not easily blown out.

FIGURE 3 is a sectional view of the plug 24 and attached fusee unit 36as taken along the line 3-3 indicated in FIGURE 2. As can be seen fromFIGURE 3, the port 26 is a hole 50 having an inner, countersunk portion52. The outer end of the hole 50 is spot-faced around it to provide therecess 38 which receives the inner end of the disc 40. The inner end ofthe disc 40 may be glued or otherwise secured in the recess 38. The endplug 24 may be made of plastic in the form of an end cap with a centralportion integrally formed therein in the shape of the initiator assemblyor fusee unit 36, with a countersunk portion to be filled with theprimer compound.

The end of the fuse 32 is inserted into the port 26 and through the hole34 such that it is located within inch of the outer face surface of thedisc 40. Molten primer compound is then poured into the countersunkportion 44 until it covers the top of the fuse 32 and is substantiallylevel with the outer face surface of the disc 40. After solidifying, theprimer compound 42 is completely covered by the adhesive cover 46. Thefuse 32, the explosive charge 30 and the points connecting with theexplosive charge 36, port 26 and the initiator assembly or fusee unit 36are suitably sealed with sodium silicate (or similar substance) to bemoisture proof.

To assemble the cartridge 10, the plug 24 with attached fusee unit 36,fuse 32 and the connecting explosive charge 30 is swage fitted to theright end 22 of casing 12 and sealed with a nonsoluble (in water) glue.The casing 12 is then gradually packed with the chemical composition 28while the fuse 32 and the explosive charge 30 are carefully arranged andpositioned. After packing the casing 12 to within inch of the left end18 of the casing 12, the ballast 14 is swage fitted into the left end 18solidly packing the chemical composition 28 in the casing 12. The entirecartridge 10 except for the adhesive cover 46 can then be painted abright color and, finally, the cartridge 10 is sealed against a moistureor fluid environment by immersing it in ordinary paraffin. A paraffincoating of, for example, at least inch is necessary to ensure that thecartridge is adequately moisture proofed.

FIGURE 4 is a simplified perspective view depicting the use of thecartridge 10 in fishing operations. The use of the cartridge 10 infishing operations is illustrated since its use in rescue operations isrelatively simple and consists of generally deploying the units at aradius between approximately 10 to feet from a floating person, in acircular scatter pattern. Each cartridge 10 is ignited by peeling offthe adhesive cover 46 and scratching the surface of the primer compound42 with the head of a primer striker (not shown) which is similar to anordinary match having a head of a particular chemical substance thatreacts with the primer compound 42 to ignite the latter. Detonation ofeach cartridge at the predetermined depth produces a cloud formation ofapproximately 24 cubic feet upon initial explosion, and these form arepellent barrier to predatory fish around the floating person. Thecloud formations spread slowly and are not dispersed or washed away veryeasily because of the dye-like and colloidal characteristics of theingredients of the chemical composition 28.

A tuna clipper 54 is shown in FIGURE 4 in the process of taking up andre-stacking part of a purse net 56 on a rotatable aft platform 58 of theclipper 54. The remainder of the net 56 has been formed into a closedcircle, the upper edge of the net 56 being supported by floats 62. Thebottom of the net 56 had been previously drawn shut by means of a winch69 which was used to wind up the purse line that passes through steelrings 64 attached to the lower edge of the net 56. As mentioned before,after the closed bottom of the net 56 is brought onto the clipper 54,one end of the net 56 is taken and 8 picked up-iover a rotated'powerblock or drum 66 which is mounted on the end of a boom.

During the netting, net pickup, brailing of the tuna and other phases,all operations are directed by a person in the crows-nest 68 mounted tomast 70 of the clipper 54. While fishing operations are clearly visiblefrom this vantage point, it is not possible to observe the action ofsharks at any depth in the water. Although it is possible to startdeploying a number of the cartridges 10 as soon as net holes appearduring pickup of the net, in order to repel and deter further attacks onthe netted tuna, a considerable amount of the tuna could be lost withattendant destruction of the net due to the well-known feeding frenzy ofsharks. In this instance, a considerable number of the cartridges 10must be deployed as fast as possible to prevent the sharks from doingmuch further damage. Thus, it is desirable that the cartridges 10 bedeployed promptly with pickup of the net 56 and continued regularlyuntil the net is formed into a relatively small bag or sack.

FIGURE 5 is another perspective of a simplified nature taken fromanother direction to illustrate the proper use of the cartridge 10during pickup of the net 56. As the net 56 is being picked or taken up,the lower curved portion 72 is being constantly moved and in motion asindicated by arrow 74. The tuna 76 at or near this moving, lower portion72 of the net 56 are easily gilled (dependent on their size), havingtheir heads caught in the meshes of the net 56, and are rolled alongwith other, possibly dead tuna in the lower portion 72 of the net 56.Apparently, at about the time that the rolling strip, which is about 21to 24 /2 fathoms down from the upper edge of the net 56, reaches andbecomes the lower portion 72 of the net 56, a particularly attractivemass of gilled and rolling tuna 76 induces the sharks toattack at aboutthat time.

By deploying the cartridges 10 in a generally circular scatter patternbefore and during pick up of the net 56, a barrier of cloud formations78 is produced to repel and deter the sharks from attacking the nettedtuna. Proper deployment of the cartridges 10 is based upon experience,consideration of heavy running tides, etc. By utilizing cartridges 10having a fuse 32 of proper length, and of correct sink rate, the cloudformations 78 will be produced at appropriate depths, as indicated,which would protect the catch from shark attack. It is to be noted thatthe cloud formations 78 not only provide a barrier which is repellent tothe sharks, they are generally opaque and obscure the tuna at the lowerportion 72 of the net 56. The sharks do not enter, except perhaps veryrarely, an opaque area. The opaqueness of the cloud formations 7 8 isdue in large measure to the fine sand in the chemical composition 28. Afairly large and opaque barrier can be created since each cartridge 10produces a cloud formation of, for example, 24 cubic feet on initialdetonation.

The cloud formations 78 at about rolling strip depth include coppersulfate or similar repellent in them if the chemical composition 28 inthe cartridges 10 originally incorporated such ingredient, of course.However, any possible contamination of the nearby netted tuna and net isentirely removed over the distance both tuna and net must move to reachthe clipper 54. Also, a relatively long time is involved before thenetted tuna is brought to the bag, and finally scooped up and depositedin the fish wells 80 (FIGURE 4) of the clipper 54. Of course, if thetoxic or disagreeable ingredient is omitted from the chemicalcomposition 28 in the cartridge 10, there is no basis for any concern ofcontamination.

Actually, though, the cartridges 10 containing the amounts of the coppersulfate ingredient as given in Example A above, may be used even withinthe net 56 without fear of any contamination to the tuna or net 56.There is, of course, no danger to a person or persons who are protectedfrom shark attacks by exploded cartridges 16 which are filled with achemical composition 28 as given in Example D, although the cloudformations pro- 9 duced by it are extremely obnoxious to sharks. Thereis also no danger to any person from the explosions of the cartridges 10if the amount of explosive charge 30 is suitably reduced for use inlifesaving or rescue operations, and the cartridges 10 are at leastseveral feet away.

Although some specific dimensions, types of material, etc. have beengiven above for the illustrative example of my invention, it is to beunderstood that the particular embodiments of the invention describedabove and shown in the drawings is merely illustrative of and notrestrictive on the broad invention, and that various changes in design,structure and arrangement may be made without departing from the spiritand scope of the appended claims.

I claim:

1. A method of preventing movement of fish between two adjacent zones ofa body of water, which comprises the steps of:

igniting external ends of respective fuses in a number of cartridgeswhich each includes a repellent material, and an explosive chargeconnecting with a corresponding one of said fuses therein;

deploying said number of cartridges into the body of water in apredetermined pattern near the common boundary of the two zones; and

creating a fish repellent barrier of cloud formations at depth byallowing said cartridges to sink substantially freely undergravitational influence at a predetermined rate in the body of water,

limiting the discharge of gas generated by said fuses, when burning,from said respective cartridges to maintain internal pressure inreasonable equilibrium with external fluid pressure to prevent prematureextinction of said fuses, and

exploding said cartridges after a predetermined time duration followingignition of the fuses of said cartridges to disperse said repellentmaterial in said cartridges into respective cloud formations, wherebypredatory fish in one of the adjacent zones will be prevented by saidbarrier from entering into the other zone. 2. A method of purse seining,which comprises the steps of:

closing a purse seine in a body of water to capture a school of fish;picking up an end of said closed purse seine into a boat and forming arelatively small bag of said purse seine; igniting external ends ofrespective fuses in a number of cartridges which each includes arepellent material, and an explosive charge connecting with acorresponding fuse therein; deploying said number of cartridges into thebody of water in a predetermined pattern near the common boundary of twoadjacent Zones during pickup of said purse seine, one of said zonesincluding the captured school of fish and the other zone including anumber of predatory fish; and creating a fish repellent barrier of cloudformations at a predetermined depth adjacent said purse seine y allowingsaid cartridges to sink substantially freely under gravitationalinfluence at a predetermined rate in the body of water, limiting thedischarge of gas generated by said fuses, when burning, from saidrespective cartridges to maintain internal pressure in reasonableequilibrium with external fluid pressure to prevent premature extinctionof said fuses, and exploding said cartridges after a predetermined timeduration following ignition of .the fuses of said cartridges to dispersesaid repellent material in said cartridges into respective cloudformations,

iii

whereby said predatory fish is prevented by said barrier from enteringinto said one of said Zones including the captured school of fish fromsaid other zone to attack the captured school of fish.

3. A method of preventing movement of fish between two adjacent zones ofa body of water, which comprises the steps of:

selecting a number of cartridges each having a predetermined free sinkrate in a fluid medium and containing a repellent material, an explosivecharge and a connecting fuse having a selected, predetermined burn time;

igniting ends of said fuses of said number of cartridges;

deploying said number of cartridges into the body of water in apredetermined pattern near the common boundary of the two zones; and

creating a fish repellent barrier of cloud formations at depth byallowing said cartridges to sink substantially freely undergravitational influence at said predetermined rate in the body of water,

limiting the discharge of gas generated by said fuses, when burning,from said respective cartridges to maintain internal pressure inreasonable equilibrium with external fluid pressure to prevent prematureextinction of said fuses, and

exploding said car-tridges after a predetermined time duration followingignition of the fuses of said cartridges to disperse said repellentmaterial in said cartridges into respective cloud formations,

whereby predatory fish in one of the adjacent zones will be prevented bysaid barrier from entering into the other zone. 4. The method as definedin claim 3 wherein said cartridges are each selected to include aballast made of material having a specific gravity of the order of atleast 2.80 to control the free gravitational sink rate of each of saidcartridges.

5. A method of purse seining, which comprises the steps of:

closing a purse seine in a body of water to capture a school of fish;

picking up an end of said closed purse seine into a boat to form arelatively small bag of said purse seine;

selecting a number of cartridges each having a predetermined free sinkrate in a fluid medium and containing a repellent material, an explosivecharge and a connecting fuse having a selected, predetermined burn time;

igniting ends of said fuses of said number of cartridges;

deploying said number of cartridges into the body of water in apredetermined pattern near the common boundary of two adjacent zonesduring pickup of said purse seine, one of said zones including thecaptured school of fish and the other zone including a number ofpredatory fish; and

creating a fish repellent barrier of cloud formations at a predetermineddepth adjacent said purse seine y allowing said cartridges to sinksubstantially freely at said predetermined rate in the body of water,

limiting the discharge of gas generated by said fuses, when burning,from said respective cartridges to maintain internal pressure inreasonable equilibrium with external fluid pressure to prevent prematureextinction of said fuses, and exploding said cartridges after apredetermined time duration following ignition of the fuses of saidcartridges to disperse said repellent ma- Ti 1 1 2 terial in saidcartridges into respective cloud References Cited by the Examinerformations near rolling strip depth of said p-urse UNITED STATES PATENTSserne, whereby said predatory fish is prevented by said barrier fromentering into said one of said zones in- 5 2:81O:229 10/1957 Allyn 434.5cluding the captured school of fish from said other 3,175,319 3 /1965Gonsalves zone to attack the captured school of fish. 6. The method asdefined in claim 5 wherein said car- FOREIGN PATENTS tridges are eachselected to have a streamlined shape and 25 555 11 /19 7 Great Britainincluding a ballast made of a material having a specific 10 I gravity ofthe order of at least 2.80 to control the free SAMUEL KOREN, PnmaryExamine!- sink rate of each of said cartridges in the body of Water. W,H, CAMP, Assistant Examiner.

1. A METHOD OF PREVENTING MOVEMENT OF FISH BETWEEN TWO ADJACENT ZONES OFA BODY OF WATER, WHICH COMPRISES THE STEPS OF: IGNITING EXTERNAL ENDS OFRESPECTIVE FUSES IN A NUMBER OF CARTRIDGES WHICH EACH INCLUDES AREPELLENT METERIAL, AND AN EXPLOSIVE CHARGE CONNECTING WITH ACORRESPONDING ONE OF SAID FUSES THEREIN; DEPLOYING SAID NUMBER OFCARTRIDGES INTO THE BODY OF WATER IN A PREDETERMINED PATTERN NEAR THECOMMON BOUNDARY OF THE TWO ZONES; AND CREATING A FISH REPELLENT BARRIEROF CLOUD FORMATIONS AT DEPTH BY ALLOWING SAID CARTRIDGES TO SINKSUBSTANTIALLY FREELY UNDER GRAVITATIONAL INFLUENCE AT A PREDETERMINEDRATE IN THE BODY OF WATER, LIMITING THE DISCHARGE OF GAS GENERATED BYSAID FUSES, WHEN BURNING, FROM SAID RESPECTIVE CARTRIDGES TO MAINTAININTERNAL PRESSURE IN REASONABLE EQUILIBRIUM WITH EXTERNAL FLUID PRESSURETO PREVENT PREMATURE EXTINCTION OF SAID FUSES, AND EXPLODING SAIDCARTRIDGES AFTER A PREDETERMINED TIME DURATION FOLLOWING IGNITION OF THEFUSES OF SAID CARTRIDGES TO DISPERSE SAID REPELLENT MATERIAL IN SAIDCARTRIDGES INTO RESPECTIVE CLOUD FORMATIONS, WHEREBY PREDATORY FISH INONE OF THE ADJACENT ZONES WILL BE PREVENTED BY SAID BARRIER FROMENTERING INTO THE OTHER ZONE.